Just released git-annex 6.20180626 with important security fixes!
Please go upgrade now, read the release notes for details about some necessary behavior changes, and if you're curious about the details of the security holes, see the advisory.
I've been dealing with these security holes for the past week and a half, and decided to use a security embargo while fixes were being developed due to the complexity of addressing security holes that impact both git-annex and external special remote programs. For the full story see past 5 posts in this devblog, which are being published all together now that the embargo is lifted.